An Integrated crop Ecosystem management Model named ICEMM was developed at the Texas A&M Research Center at Corpus Christi. ICEMM was developed as a research tool for the design and evaluation of management option and cropping systems adapted to the Lower Coastal Bend Region of Texas. The development of ICEMM capitalizes on the existence of models of soil processes, insect pests, cotton and sorghum growth and yield and economic decision-aid algorithms. A Graphics User Interface (GUI) was developed for file management and for the dynamic display of simulated data. The approach used in ICEMM to display simulated output is a distinctive characteristic of the model. The system uses a modified version of GOSSYM for the simulation of cotton growth and yield. Some of the variables simulated in the insect component of ICEMM are: a) insect pests such as boll weevil, tobacco budworm/bollworm, fleahopper and pink bollworm, b) insect predators and parasites, c) insecticide control and d) host-plant resistance. In order to simulate dryland cotton systems, mechanisms of GOSSYM dealing with plant water relations, plant height, stem dry weight and square and young green boll abscission were modified. The economic component of ICEMM views decision making under risk and uncertainty situations. Historical weather data are used to predict cotton lint yields for various management strategies and to estimate the probabilities associated with these yield outcomes. The calibration of the model was performed using data for four cultivars collected during the 1989, 1990 and 1991 growing seasons at Corpus Christi, TX, for cultivars DPL-50, DPL-51, DES-119, CAB-CS and HQ 95. Once Calibrated the model simulated commercial dryland cotton field in Kingsville, TX and Irrigated fields in Mississippi. On the average the simulated yields were within 12.7% of the observed yields. Results indicate that the model is sufficiently accurate in predicting cotton growth and yield to be used for system analysis of crop production alternatives.